Incorporation of passive components such as resistors and capacitors into conventional semiconductor circuitry enables analog and radio-frequency (RF) circuitry. While the manufacture of resistors in a semiconductor substrate involves only the formation of a patterned doped semiconductor area or a silicided area, and therefore is relatively straightforward to implement, manufacture of capacitors involves formation of a capacitor dielectric and two conductive plates on both sides of the capacitor dielectric, and therefore requires relatively involved processing steps.
In the prior art, deep trench capacitors are widely used in dynamic random access memory (DRAM) devices. While deep trenches offer high capacitance per area, formation of deep trench capacitors requires dedicated processing steps such as the formation of deep trenches by etching, formation of buried plates, filling of the inside of the deep trenches, and subsequent planarization. Similarly, stack capacitors are known in the prior art. To form stack capacitors, dedicated processing steps are used in the middle-of-line (MOL) level to form capacitors with high capacitance per area. Metal-insulator-metal capacitors (MIMCAPs) are also known in the prior art, in which metal levels are used as two plates of a capacitor structure and a dielectric layer is formed between the two plates within a BEOL wiring level. MIMCAPs require a low number of processing steps and less processing complexity compared with deep trench capacitors, while offering less capacitance per area. Further, gate dielectric based capacitors are known in the prior art, in which the gate dielectric is also utilized as a capacitor dielectric. While offering less processing complexity, gate dielectric based capacitors offer less capacitance per area as well as higher leakage current compared with deep trench capacitors since gate dielectrics typically have higher per area leakage current than dedicated capacitor dielectric under similar operating conditions. In addition, gate dielectric based capacitors typically have less conductive silicon bottom plates unless an additional ion implant is implemented to increase the conductivity of the bottom plate. These capacitors are typically non-linear.
In summary, prior art solutions for capacitors in semiconductor circuitry either have high leakage or require complex processing steps involving multiple mask levels. In other words, to form a low leakage capacitor in a semiconductor substrate according to the prior art, at least one and often times many mask levels are needed as well as many associated processing steps.
Therefore, there exists a need for a capacitor structure that offers low leakage current while requiring minimal processing complexity for manufacturing and methods of manufacturing the same
Further, there exists a need for a capacitor structure that requires minimal incremental processing cost and minimal or no increase in the number of lithographic masks and methods of manufacturing the same.